A Gramercy Park doctor and his assistant sold thousands of oxycodone scrips in two separate trafficking operations that poured more than half a million pills into the hands of dealers and junkies across the Northeast, authorities charged yesterday.

Dr. Hector Castro, 51, had no clue that his office manager, Patricia Valera, 28 — who went by the nickname “Kardashian” — was selling his scrips to a massive drug ring involving dozens of dealers across New York, Jersey, Pennsylvania and Massachusetts, prosecutors said.

Meanwhile, Castro ran his own, parallel operation out of his Itzamma Medical Center — selling more than 5,100 prescriptions to junkies in New York and Jersey to the tune of more than $637,000, records show.

The scheme netted Valera — who reportedly earned her Kardashian nickname because of her luxe fashion tastes — at least $356,500 between August 2009 and March 2013, law-enforcement authorities said.

“How many people died so [Valera] could buy a Louis Vuitton bag?” said Bridget Brennan, chief of the city’s Special Narcotics Prosecutor’s Office. “How many people became addicted?”

Officials launched a probe into the practice when a Woodbridge, NJ, man overdosed in December 2011 on the highly-addictive painkiller a day after filling a prescription signed by Castro.

Authorities say they soon uncovered Castro’s and Valera’s involvement with interstate drug dealings that diverted more than 500,000 pills worth $10 million to the black market.

Dr. Castro allegedly pumped out thousands of scrips at $125 a piece.

But the business-savvy Valera went a step beyond — she allegedly swiped hundreds of scrips from the doctor and sold them to drug dealers at the top of massive operations in Pennsylvania for $500 a pop.

“Smart business woman, I guess,” Brennan said.

“There’s no price control on this kind of trafficking.”

Castro — who founded the Itzamna Medical Center in 2001 — was arrested at his Hell’s Kitchen home on Tuesday and is being held in lieu of $500,000 bond on drug trafficking charges.

He pleaded not guilty in Manhattan Supreme Court and faces more than 200 years in prison.

Cops seized $20,000 in cash from a locked box in his house alongside medical records and computer equipment.

Valera was arrested alongside her husband, Hector Rodriguez, on Tuesday in their Bronx home, where police also found a loaded handgun and about $8,000 in cash and blank prescriptions. She pleaded not guilty.

Three other people were also arrested in New York and New Jersey.

Another 43 are charged in Pennsylvania — the largest drug take down in the state’s history, cops said. Police seized 30 weapons from the criminals, records show.